An airbag for motor vehicles is designed to protect a vehicle occupant in the event of an accident. Problematic situations arise in cases where the vehicle occupant is not in his or her normal sitting position when the airbag deploys. Such situations, also known as xe2x80x9cout of positionxe2x80x9d or OOP cases, are particularly significant for children who are not accommodated as prescribed in children""s seats. The present invention addresses this problem.
The present invention relates to an airbag arrangement for a motor vehicle having at least one inflatable airbag deployable in a direction to protect a vehicle occupant, and at least one arrangement associated with the airbag for limiting an unfolding impulse of the airbag upon an obstacle placed in a deployment path of the airbag to reduce the unfolding impulse transferred to the obstacle.
Under a normal situation, the airbag is inflated in the direction to intercept the occupant to cushion the impact. The limiting arrangement for limiting the inflating impulse of the airbag can be influenced by an obstacle, such as the occupant. The limiting arrangement can reduce the inflating impulse directed to the obstacle, which is located in the path of the airbag expansion or movement.
The limiting arrangement is designed to prevent the airbag from deploying its full unfolding impulse in the OOP cases, i.e., when the respective vehicle occupant is out of his normal position and situated in the path of the airbag deployment, but allows full unfolding impulse in the normal unimpeded situation, i.e., when the vehicle occupant is in his normal position. Since an obstacle, such as a vehicle occupant, influences the limitation arrangement, it automatically recognizes the OOP cases, whereupon the present limiting arrangement thereof automatically reduces the unfolding impulse of the airbag.
The limitation arrangement can be formed such that it responds based on the resistance of the obstacle located outside the normal seating position, in the deployment path. The resistance created by the obstacle against the deploying airbag thus controls the unfolding or inflating impulse. Since the limitation arrangement responds to the obstacle this way, the occupant who is not in his or her normal sitting position and located in the deployment path of the airbag triggers the response of the limitation arrangement to reduce the inflation force of the airbag.
Alternatively, it is also possible according to the present invention for the limitation arrangement to be formed such that it responds to the lack of resistance from the occupant. In this case, the limitation arrangement can detect an OOP situation by the lack of resistance, which is normally present if the occupant is properly located in the normal seating position. The present airbag arrangement allows a greater protection for the respective vehicle occupant, even in the OOP cases.
In one embodiment of the invention, the limitation arrangement can comprise the airbag sheath. The airbag sheath, in the case of a folded airbag, can be made to have a lower degree of unfolding in one direction, e.g., in the direction of deployment, than approximately perpendicular to that direction.
It is therefore possible to achieve a limitation of the unfolding impulse of the airbag sheath and thus a reduction in its inflation force without any additional means, simply through the uneven degree of unfolding of the airbag, uneven particularly with respect to the direction of deployment. The inflation of the airbag is substantially harmonized by the lower degree of unfolding in the direction of airbag deployment so that the inflation process is associated with a substantially lower force or drive. Here, the airbag is inflated predominantly in the direction of deployment due to the higher degree of unfolding perpendicular to the direction of deployment. The airbag is preferably folded together such that it has a large expansion perpendicular to the direction of deployment and takes up at least the substantial part of the space available in this direction. This allows an extremely areal arrangement of the folded airbag to be achieved, which substantially reduces its unfolding impulse. The direction of the lower degree of unfolding does not have to agree exactly with the direction of deployment, but can also deviate therefrom.
The folded airbag can here be arranged areally along a contact surface located in the deployment path and has, in particular, areal contact to the contact surface. The contact surface preferably extends at least approximately perpendicular to the direction of deployment.
It is further preferred to have the contact surface formed by an airbag cover. The airbag can, for example, be arranged at or in a vehicle seat, with a seat cover provided as the airbag cover, which is initially expandable and which can subsequently be ripped open, particularly by the inflation of the airbag. The seat cover can here be provided with a ripping seam.
With an expandable seat cover, the airbag arranged according to the invention can be positioned under the seat cover in a favorable manner with respect to the OOP case at the beginning of the inflation process before it deploys further by the ripping open of the seat cover.
According to a further preferred embodiment of the invention, the limitation arrangement can be configured such that when the obstacle is located outside the normal seating position, in the deployment path, the obstacle blocks the deployment path to limit the space for deploying the airbag. The limited space configures the airbag to prevent the airbag from reaching a threshold pressure in the airbag, which is only reachable in a normal protection case resulting from opposite external reaction forces generated when the occupant is in a normal seating position.
The inflating airbag thus can be under less stress in the OOP case than in the normal protection case. For example, in the case of a side airbag arranged at the side of the backrest of a vehicle seat, the high pressure required to cancel the limitation is achieved in the airbag by the reaction forces exerted by the occupant in his normal position and the side panel of the vehicle when the airbag forces its way between the vehicle occupant and the side panel during inflation.
These reaction forces are not present in the OOP case so that the pressure build-up required to break through the limitation is not carried out in the airbag and the airbag is inflated within the limitation, whereby the unfolding impulse and thus the inflation force of the airbag is reduced.
In another embodiment according to the present invention, the limitation arrangement is formed by a limitation sheath surrounding the folded airbag at least partially, and whose maximum expandability in the direction of deployment is smaller than that of the airbag. The limitation sheath can be attached to that assembly of the vehicle at or in which the airbag is arranged, for example at a vehicle seat or a seat cover. Alternatively, the limitation sheath can also be attached to the airbag itself. It is further possible to provide the limitation sheath as a component of the airbag.
According to another embodiment of the present invention, the airbag comprises at least two sections, a primary section and a secondary section, that are inflatable sequentially one after another. The limitation arrangement can comprise at least one valve between these sections. The valve can be closed when the folded airbag is blocked by the resistance of the obstacle located outside the normal position and can be opened by the inflation of the primary section of the airbag, which is inflatable first if there is no such resistance.
A vehicle occupant located outside his normal position automatically ensures that the valve arranged between the two part volumes of the airbag remains closed. The inflation volume of the airbag thus remains limited to the volume of the primary section, whereby the inflation force of the airbag is reduced in a manner advantageous in the OOP case. The valve can be closed by the folded secondary section of the airbag.
The valve can be formed by a nozzle section formed with at least one aperture. The nozzle section can be pushed over, folded, over, flipped over or bent over, in particular against the direction of deployment, to block the aperture. This nozzle section can be formed, in particular, tubular, hose, or snorkel configuration. The cross-section of this section can be approximately circular, but generally can have any geometry deviating from a circular shape.
The nozzle section forming the valve can be formed at a partition wall arranged in the airbag sheath, separating the two sections of the airbag from one another. The partition wall can be a material layer sewn into the airbag sheath.
According to a further variant of the invention, the limitation arrangement can comprise at least one discharge aperture formed in the airbag sheath. The aperture is closed in the normal protection position, but allows gas to escape when an obstacle blocks the airbag.
The gas can be blown into the airbag with at least one gas generator to inflate the airbag. The gas can escape from the airbag through the discharge aperture in the OOP case, whereby the unfolding impulse of the airbag is reduced. The closing the discharge opening in the normal protection case ensures that the airbag can be fully inflated and can assume its protective position.
The limitation arrangement can further include a closing arrangement for closing the discharge aperture arranged in the airbag or airbag sheath. The closing arrangement is configured to close the aperture when the airbag is deployed without the obstacle in the deployment path. That is, it is switchable to at least partially close the aperture when unfolding of the airbag increases in the normal protection case.
This way, a reversible closure for the discharge opening is created by the unfolding of the airbag, with such closure being automatically switched to the state closing the discharge aperture in the normal protection case in which the airbag can unfold without hindrance. The unfolding of the airbag is blocked in the OOP case by the obstacle formed by the occupant located outside his normal position so that the closing arrangement cannot be switched to the closing position. The discharge aperture consequently remains open in the OOP case so that gas can escape from the airbag, whereby its unfolding impulse is reduced.
The closing arrangement can comprises at least one material layer connected, in particular sewn, to the airbag sheath, with the connection being releasable at least in regions by the inflating of the airbag.
It is advantageous here for a connection releasable by the inflating of the airbag to be provided in a region of the airbag located at the front in the direction of deployment, while the material layer is fixed to the airbag sheath in an inflation-resistant manner in a region located at the back in the direction of deployment.
In another embodiment, the closing arrangement, formed in particular by a material layer, is connected in an inflation-resistant manner to the airbag sheath, with the material layer contacting the airbag sheath and closing the discharge aperture at least in part in the normal protection case with the airbag inflated at least in part.
It can be achieved this way, without releasable connections between the closing arrangement, i.e., the material layer, and the airbag sheath and by a corresponding design and/or arrangement of the material layer, that the material layer contacts the airbag sheath and closes the discharge aperture at an advanced stage of the inflation process. The advanced stage of the inflation process required for a closing of the discharge aperture is not achieved in the OOP case due to the vehicle occupant forming an obstacle, which is in the way of the deploying airbag so that the discharge aperture remains in an unclosed state and gas can escape from the airbag, whereby the unfolding impulse of the airbag and thus its inflation force is reduced.
According to a further variant embodiment according to the invention, the discharge aperture can be moved away from an external closing surface at least partly closing the discharge aperture in the normal protection case by the inflation of the airbag when the obstacle is outside the normal position.
The limitation arrangement formed by the discharge opening thus responds here to the lack of resistance of the obstacle by creating a gas escape possibility by the discharge aperture moving away from the closing surface, whereby the unfolding impulse of the airbag is reduced. In contrast, when a vehicle occupant assuming his or her normal position forms the obstacle in the normal protection case, the airbag cannot deploy in a manner such that the discharge aperture is moved away from the closing surface. Since the discharge aperture remains at least partly closed in the normal protection case, the airbag can be inflated in the preset manner and meet its protective function.
The closing surface can be formed by the assembly of the vehicle at or in which the airbag is arranged, for example by a side panel of the vehicle or by a vehicle seat.
The airbag arrangement can be a side airbag arrangement integrated in a vehicle seat or in a vehicle side panel. The invention can, however, generally be employed with any imaginable airbag arrangement, e.g., in conjunction with a front airbag arrangement for the driver or front-seat passenger or with airbag arrangements arranged in the corresponding positions relative to a vehicle seat in order to protect certain body regions of an occupant, e.g., the knee or the feet.
The various embodiments and features of the limitation arrangements described above, and in detail below, can be combined with one another.